一维动静组合载荷下灰岩力学特性研究

发布时间：2018-04-18 23:02

本文选题：岩爆 + 岩石力学　；参考：《昆明理工大学》2014年硕士论文

【摘要】：岩爆发生在高地应力条件下隧道或矿山等地下工程开挖过程中,是一种非常严重的动力灾害,受到国内外学者越来越多的重视。为了从本质上了解岩爆的特性,以预防岩爆的发生,必须从岩石受载的力学响应着手进行研究。为此,本文采用霍普金森杆试验系统(SHPB),对灰岩进行一维动静组合载荷试验,在实验基础上,通过Flac3D软件对该试验过程进行数值模拟分析,综合采用试验和数值模拟结合的方法来研究岩石受到动力冲击作用时的力学特性,以模拟深部岩体“高应力+动力扰动”的受力模式,为研究岩爆的发生机理和力学本质提供一定的参考。试验研究表明：1)当灰岩受到冲击载荷作用没有严重破坏时,其应力-应变曲线在应力峰值后期一般会呈现出特有的“应变回弹”现象；当岩石破坏严重时,应力峰值后期则不会出现“应变回弹”现象,而是表现出和静载实验相类似的曲线走势。2)在应变率相近的条件下,随着轴压的增加,灰岩动态强度会先增大后减小,当轴压超过某一限值(岩石静载强度的56%-71%之间)时,岩体的承载能力开始下降；在轴压一定的条件下,随着应变率的增加,岩体动静组合强度逐渐增大。3)在无轴压条件下,灰岩受冲击后全部表现为吸能状态,而在有轴压条件下部分岩样则呈现释能状态；随着轴压的增加,岩石吸收的能量逐渐减小,直至最后开始表现为释放能量。数值模拟表明：1)随着轴压的增大,动载荷在岩体内部所形成的轴向应力逐渐减小位移逐渐增大；随着动载幅值的增加,动载荷在岩体内部所形成的轴向应力逐渐增大,位移也逐渐增大；随着动载频率的增加,动载荷在岩体内部所形成的轴向应力变化不大,但位移逐渐减小。2)轴向静压和动载幅值决定了岩体内部的轴向应力分布情况,动载频率对其影响不大；而动载荷幅值和动载频率则是岩体内部位移的主要影响因素,轴向静压对其影响不大。3)动载幅值和动载频率的增大,都会导致岩体受冲击的平均应变率增加,轴向静压与应变率的相关性不大。4)通过对岩体内各位置的实时监测发现,岩体内各点的轴向位移到达峰值后均出现位移减小的现象,这与试验中的“应变回弹”现象是一致的。本文采用室内动静组合加载实验和数值模拟相结合方法,对岩体一维动静组合加载力学特性进行分析,研究结果可为深部矿山岩爆机理和预测预报提供实验依据和参考。
[Abstract]:Rock burst occurs in the excavation process of underground projects such as tunnels or mines under high ground stress. It is a very serious dynamic disaster and has been paid more and more attention by scholars at home and abroad.In order to understand the nature of rock burst and prevent the occurrence of rock burst, it is necessary to study the mechanical response of rock load.In this paper, the Hopkinson bar test system is used to carry out the one-dimensional dynamic and static loading test of limestone. On the basis of the experiment, the numerical simulation analysis of the test process is carried out by Flac3D software.In order to simulate the "high stress dynamic disturbance" of deep rock mass, the mechanical properties of rock subjected to dynamic impact are studied by means of the combination of test and numerical simulation.It provides a certain reference for studying the mechanism and mechanical nature of rock burst.The experimental results show that when limestone is not seriously damaged by impact load, the stress-strain curve usually presents a special "strain rebound" phenomenon at the later stage of the stress peak, and when the rock is seriously damaged, the stress-strain curve usually presents a unique "strain springback" phenomenon at the later stage of the stress peak.In the later stage of the stress peak, the phenomenon of "strain rebound" will not appear, but the curve trend .2similar to that of the static load experiment.) under the condition of similar strain rate, with the increase of axial compression, the dynamic strength of limestone will first increase and then decrease.When axial compression exceeds a certain limit (between 56% and 71% of the static load strength of rock), the bearing capacity of rock mass begins to decrease, and under certain axial compression conditions, the strength of rock mass dynamic and static assemblage increases gradually with the increase of strain rate. 3) under the condition of no axial compression,The limestone exhibits energy absorption state after impact, while some rock samples show energy release state under axial pressure. With the increase of axial pressure, the energy absorbed by the rock gradually decreases, until the last performance is energy release.The numerical simulation shows that with the increase of axial compression, the axial stress formed by the dynamic load in the rock body gradually decreases and the displacement increases, and with the increase of the amplitude of the dynamic load, the axial stress formed by the dynamic load in the rock body increases gradually.With the increasing of dynamic load frequency, the axial stress formed by dynamic load in rock mass changed little, but the displacement gradually decreased. 2) Axial static pressure and dynamic load amplitude determined the axial stress distribution in rock mass.The amplitude of dynamic load and frequency of dynamic load are the main influencing factors of internal displacement of rock mass, but axial static pressure has little effect on the amplitude of dynamic load and frequency of dynamic load.The correlation between axial static pressure and strain rate is not significant. Through the real-time monitoring of each position of rock mass, it is found that the axial displacement of each point in rock mass decreases after reaching the peak value.This is consistent with the "strain rebound" phenomenon in the experiment.In this paper, the mechanical characteristics of one-dimensional dynamic and static combined loading of rock mass are analyzed by the combination of indoor dynamic and static loading experiments and numerical simulation. The results can provide experimental basis and reference for the mechanism of rock burst and prediction and prediction of rock burst in deep mines.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU45

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